Center bearing bush unit for propeller shaft

ABSTRACT

A center bearing bush unit for a propeller shaft can effectively decrease the amount of large/small displacement that occurs in the propeller shaft during driving of a vehicle. A center bearing bush unit for a propeller shaft includes an inner pipe; an outer pipe disposed on a common axis as the inner pipe at the outside of the inner pipe; a cushion rubber attached between the inner and outer pipes, and having a plurality of voids disposed on the common axis; and a plurality of stoppers attached to the outer circumferential surface of the inner pipe while being spaced apart from the cushion rubber at a predetermined interval.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Divisional of U.S. patent application Ser.No. 14/802,128, filed Jul. 17, 2015, which is a Divisional of U.S.patent application Ser. No. 14/010,388, filed Aug. 26, 2013, whichclaims priority of Korean Patent Application Number 10-2012-0158056filed Dec. 31, 2012, the entire contents of which applications areincorporated herein for all purposes by these references.

BACKGROUND OF INVENTION

Field of Invention

The present invention relates to a center bearing bush unit for apropeller shaft. More particularly, the present invention relates to acenter bearing bush unit for a propeller shaft, which can effectivelydecrease the amount of large/small displacement that occurs in thepropeller shaft during driving of a vehicle.

Description of Related Art

In general, a rear-wheel or four-wheel drive vehicle has a propellershaft that transmits power output from an engine up to a differentialvia a transmission. In a case where the length of the propeller shaft islong, the propeller shaft is formed into a two-piece structure. In thetwo-piece structure, a center bearing bush unit assembled with a body ofthe vehicle is provided at a central portion of the propeller shaft.

FIG. 1 is a configuration view showing a partial section of a centerbearing bush unit for a propeller shaft according to a related art.

As shown in FIG. 1, the center bearing bush unit 20 according to therelated art is mounted between a center bearing 21 and a mountingbracket 23 so as to reduce the movement of a propeller shaft 27 and toattenuate vibrations. Simultaneously, the center bearing bush unit 20prevents friction between the center bearing 21 and the mounting bracket23.

However, the center bearing bush unit 20 is made of a rubber materialhaving a simple shape. Therefore, the center bearing bush unit 20 doesnot effectively absorb movements and vibrations of the propeller shaft27 with respect to large and small displacements caused during drivingof a vehicle.

Particularly, in a case where a large-displacement movement of thepropeller shaft 27 occurs in sudden start or acceleration of thevehicle, the center bearing bush unit 20 does not effectively reduce theamount of movement of the propeller shaft 27, and hence the movement ofthe propeller shaft 27 is transmitted to a vehicle body as it is.Therefore, the ride comfort of the vehicle is deteriorated, and thefatigue degree of the center bearing bush unit 20 is increased, therebydeteriorating the durability of the center bearing bush unit 20.

Accordingly, Korean Patent Application Publication No. 2011-38505 hasdisclosed a center bearing bush unit for a propeller shaft in order todecrease large- and small-displacement movements of the propeller shaft.

In Korean Patent Application Publication No. 2011-38505, as shown inFIGS. 2 and 3, the center bearing bush unit 10 is mounted between acenter bearing 7 mounted to a propeller shaft 1 and a mounting bracket 9fixed to a vehicle body frame while surrounding the center bearing 7.The center bearing bush unit 10 is configured with a bush body 11provided by integrally forming a projection 13, first/second modifiedguide grooves 15 and 17 and a rib stopper 19. One will appreciate thatsuch integral components may be monolithically formed. Thus, the centerbearing bush unit 10 decreases small- and large-displacement movementsof the propeller shaft 1, caused during driving of a vehicle.

However, the center bearing bush unit 10 has a complicated shape, andtherefore, the tuning of the center bearing bush unit 10 is difficultwhen a change in characteristic of the center bearing bush unit 10 isrequired due to a change in operational environment.

In addition, the durability of the first/second modified guide grooves15 and 17 is structurally weak, and therefore, it is highly likely thatcracks may occur in a test for the durability of the center bearing bushunit 10. Since upper and lower gaps A and B are identical to each other,based on FIG. 3, it is difficult to absorb the amount of displacementcaused by the weight of the propeller shaft. Therefore, the vibrationinsulation performance is degraded due to the difference in rigiditybetween upper and lower portion of the center bearing bush unit.

The information disclosed in this Background section is only forenhancement of understanding of the general background of the inventionand should not be taken as an acknowledgement or any form of suggestionthat this information forms the prior art already known to a personskilled in the art.

BRIEF SUMMARY

Various aspects of the present invention provide for a center bearingbush unit for a propeller shaft, in which a cushion rubber fordecreasing the amount of small-displacement movement of the propellershaft and a stopper for decreasing the amount of large-displacementmovement of the propeller shaft are independently configured, and thecenter bearing bush unit is formed into a simple structure in which itstuning is easily performed, so that it is possible to effectivelydecrease the amount of large/small displacement of the propeller shaft,caused during driving of a vehicle.

Various aspects of the present invention provide for a center bearingbush unit for a propeller shaft, including: an inner pipe; an outer pipedisposed on the same axle as the inner pipe at the outside of the innerpipe; a cushion rubber attached between the inner and outer pipes, andhaving a plurality of voids disposed on the same axle; and a pluralityof stoppers attached to the outer circumferential surface of the innerpipe while being spaced apart from the cushion rubber at a predeterminedinterval.

The stopper may be configured with inner and outer stoppers havingdifferent diameters. One end portion of the inner stopper may beinserted into the inner void of the cushion rubber in a state in whichthe inner circumferential surface of the inner stopper is attached tothe outer circumferential surface of the inner pipe, and one end portionof the outer stopper may be inserted into the outer void of the cushionrubber in a state in which the inner circumferential surface of theouter stopper is attached to the outer circumferential surface of theinner pipe.

Various aspects of the present invention provide for a center bearingbush unit for a propeller shaft, including: an inner pipe; an outer pipedisposed on the same axle as the inner pipe at the outside of the innerpipe; a cushion rubber attached between the inner and outer pipes, andhaving a plurality of voids disposed on the same axle; and a pluralityof stoppers attached to the inner circumferential surface of the outerpipe while being spaced apart from the cushion rubber at a predeterminedinterval.

The stopper may be configured with inner and outer stoppers havingdifferent inside diameters. One end portion of the inner stopper may beinserted into the inner void of the cushion rubber in a state in whichthe outer circumferential surface of the inner stopper is attached tothe inner circumferential surface of the outer pipe, and one end portionof the outer stopper may be inserted into the outer void of the cushionrubber in a state in which the outer circumferential surface of theouter stopper is attached to the inner circumferential surface of theouter pipe.

Various aspects of the present invention provide for a center bearingbush unit for a propeller shaft, including: an inner pipe; an outer pipedisposed on the same axle as the inner pipe at the outside of the innerpipe; a cushion rubber attached between the inner and outer pipes, andhaving a plurality of voids disposed on the same axle; an inner stopperattached to the outer circumferential surface of the inner pipe whilebeing spaced apart from the cushion rubber at a predetermined interval;and an outer stopper attached to the inner circumferential surface ofthe outer pipe while being spaced apart from the cushion rubber at apredetermined interval.

One end portion of the inner stopper may be inserted into the inner voidof the cushion rubber in a state in which the inner circumferentialsurface of the inner stopper is attached to the outer circumferentialsurface of the inner pipe, and one end portion of the outer stopper maybe inserted into the outer void of the cushion rubber in a state inwhich the outer circumferential surface of the outer stopper is attachedto the inner circumferential surface of the outer pipe.

Various aspects of the present invention provide for a center bearingbush unit for a propeller shaft, including: an inner pipe; an outer pipedisposed on the same axle as the inner pipe at the outside of the innerpipe; a cushion rubber attached between the inner and outer pipes, andhaving a plurality of voids disposed on the same axle; an outer stopperattached to the outer circumferential surface of the inner pipe whilebeing spaced apart from the cushion rubber at a predetermined interval;and an inner stopper attached to the inner circumferential surface ofthe outer pipe while being spaced apart from the cushion rubber at apredetermined interval.

One end portion of the inner stopper may be inserted into the inner voidof the cushion rubber in a state in which the outer circumferentialsurface of the inner stopper is attached to the inner circumferentialsurface of the outer pipe, and one end portion of the outer stopper maybe inserted into the outer void of the cushion rubber in a state inwhich the inner circumferential surface of the outer stopper is attachedto the outer circumferential surface of the inner pipe.

The voids provided in the cushion rubber may be formed to have the samewidth, or may be formed to have selected two or more different widths.

The void may be provided with an inner void formed adjacent to the innercircumferential surface of the cushion rubber, and an outer void formedadjacent to the outer circumferential surface of the cushion rubber.

The inner and outer stoppers may be formed to have differentthicknesses, or may be formed to have the same thickness.

The cushion rubber may have a plurality of openings arranged in thecircumferential direction thereof. The cushion rubber may have apredetermined thickness in the circumferential direction thereof, or mayhave a variable thickness variably formed.

At least one of the inner and outer stoppers may have a plurality ofopenings arranged in the circumferential direction thereof. The at leastone of the inner and outer stoppers may have a predetermined thicknessin the circumferential direction thereof, or may have a variablethickness variably formed.

In the center bearing bush unit for the propeller shaft according to thepresent invention, the vibration insulation zone or rigiditycharacteristic zone of vibrations of various displacements is subdividedand expanded according to displacement conditions, thereby effectivelyinsulating vibrations. When a change in characteristic is required dueto a change in operational environment, it is possible to easily tunethe center bearing bush unit

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration view showing a partial section of a centerbearing bush unit for a propeller shaft according to a related art;

FIG. 2 is a configuration view showing a partial section of a centerbearing bush unit for a propeller shaft according to another relatedart;

FIG. 3 is a sectional view showing the center bearing bush unit of FIG.2;

FIG. 4 is a sectional configuration view showing an exemplary centerbearing bush unit for a propeller shaft according to the presentinvention;

FIG. 5A is a partial perspective view showing an exemplary dividedcenter bearing bush unit for a propeller shaft according to the presentinvention;

FIG. 5B is a partial perspective view showing a basic structure of thecenter bearing bush unit of FIG. 4;

FIG. 6A and FIG. 6B are a partial perspective and side views,respectively, showing a cushion rubber of FIG. 4 and FIG. 5A;

FIG. 7A and FIG. 7B are partial views showing outer and inner stoppers,respectively, of FIG. 4 and FIG. 5A;

FIG. 8 is an exemplary view showing shapes obtained by variably applyingthe thickness of the cushion rubber in a circumferential directionaccording to the present invention;

FIG. 9 is an exemplary view showing exemplary voids of cushion rubbers(a) through (i) and applications of the stopper according to the presentinvention;

FIG. 10 is a graph showing a rigidity of the center bearing bush unit inthe diameter direction according to the present invention;

FIG. 11 is a sectional configuration view showing an exemplary centerbearing bush unit for a propeller shaft according to the presentinvention;

FIG. 12 is a sectional configuration view showing an exemplary centerbearing bush unit for a propeller shaft according to the presentinvention; and

FIG. 13 is a sectional configuration view showing an exemplary centerbearing bush unit for a propeller shaft according to the presentinvention.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the present invention as disclosed herein,including, for example, specific dimensions, orientations, locations,and shapes will be determined in part by the particular intendedapplication and use environment.

In the figures, reference numbers refer to the same or equivalent partsof the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

The present invention provides a center bearing bush unit for apropeller shaft, which can improve the amount of large/smalldisplacement of the propeller shaft, caused during driving of a vehicle.In the present invention, a multi-level insulation characteristic zoneis implemented, so that it is possible to effectively decreasevibrations of various displacements from a small-displacement vibrationoccurring during driving to a large-displacement vibration occurring inoscillation.

FIG. 4 is a sectional configuration view showing a center bearing bushunit for a propeller shaft according to various embodiments of thepresent invention. FIG. 5A is a partial perspective view showing thedivided center bearing bush unit for a propeller shaft of FIG. 4.

The center bearing bush unit of the present invention is provided in acircular ring shape having an opened center. As shown in FIG. 4, thecenter bearing bush unit includes an inner pipe 110, an outer pipe 120,and a cushion rubber 130 and stoppers 141 and 142, which are mountedbetween the inner and outer pipes 110 and 120.

The inner and outer pipes 110 and 120 are disposed on a common axiswhile being provided as hollow cylindrical pipes. The inner pipe 110 ispositioned inside the outer pipe 120.

Although shown in this figure, in order to insulate the displacementmovement of a propeller shaft, caused during driving a vehicle, theinner pipe 110 is attached to the outer circumferential surface of acenter bearing mounted on the propeller shaft, and the outer pipe 120 isattached to the inner circumferential surface of a mounting bracketcoupled to a vehicle body while surrounding the center bearing.

In this case, the center bearing supports the propeller shaft to berotatable with respect to the vehicle body, and the mounting bracket isattached to the outer circumferential surface of the outer pipe 120 soas to fix the outer pipe 120 to the vehicle body.

That is, the center bearing bush unit of the present invention isconfigured between the center bearing mounted on the propeller shaft andthe mounting bracket fixing the center bearing to the vehicle body so asto insulate vibrations of the propeller shaft.

The inner circumferential surface of the cushion rubber 130 is attachedto the outer circumferential surface of the inner pipe 110, and theouter circumferential surface of the cushion rubber 130 is attached tothe inner circumferential surface of the outer pipe 120. The cushionrubber 130 always supports the load acting between the inner and outerpipes 120.

The cushion rubber 130 has at least one void in order to effectivelyinsulate a small-displacement vibration caused during driving, and mayhave a plurality of voids.

As shown in FIGS. 4 and 5A, the void of the cushion rubber 130 has ashape in which the cushion rubber 130 is bent in a predetermineddirection at every section in the radial direction. Thus, the void ofthe cushion rubber 130 is an empty space formed at the bent portion. Thevoid of the cushion rubber 130 may be formed with an inner void 131 andan outer void 132, which are disposed on a common axis.

The inner void 131 may be formed in the shape of a circular ringadjacent to the inner circumferential surface of the cushion rubber 130,and the outer void 132 may be formed in the shape of a circular ringadjacent to the outer circumferential surface of the cushion rubber 130.

In this case, the inner and outer voids 131 and 132 may be formed todifferent widths (see D1 and D2 of FIG. 4), or may be formed to have thesame width (see D3 and D4 of FIG. 6A).

That is, the plurality of voids provided in the cushion rubber 130 maybe formed to have the same width, or may be formed to have selected twoor more different widths.

In various embodiments and as shown in FIG. 4, the outer void 132 isformed to have a width greater than that of the inner void 131.

In this case, the inner and outer voids 131 and 132 have one sidesopened toward the opposite directions to each other, based on the axisline direction of the cushion rubber 130. The stoppers 141 and 142 arepartially inserted through the opened one side of the void.

The stoppers 141 and 142 are configured to effectively insulate alarge-displacement vibration caused during driving of the vehicle. Thestoppers 141 and 142 may be configured with at least one stopper, andmay be configured in plural numbers.

As shown in FIGS. 4 and 5A, the stopper 141 and 142 may be configuredwith inner and outer stoppers 141 and 142 having different diameters.

The inner and outer stoppers 141 and 142 are provided in the shape of anapproximately circular ring. Each of the inner and outer stoppers 141and 142 has a sectional structure in which the stopper is bent in a ‘

’ shape as shown in FIG. 7.

One end portion of the inner stopper 141 is inserted into the inner void131 of the cushion rubber 130 in a state in which the innercircumferential surface of the inner stopper 141 is attached to theouter circumferential surface of the inner pipe 110. One end portion ofthe outer stopper 142 is inserted into the outer void 132 of the cushionrubber 130 in a state in which the inner circumferential surface of theouter stopper 142 is attached to the outer circumferential surface ofthe inner pipe 110.

In this case, the inner stopper 141 is positioned to be spaced apartfrom the cushion rubber 130 and the wall surface of the inner void 131at a predetermined interval. The outer stopper 142 is positioned to bespaced apart from the cushion rubber 130 and the wall surface of theouter void 132.

The inner and outer stoppers 141 and 142 may be formed to have differentthicknesses (see S1 and S3 of FIG. 4), or may be formed to the samethickness.

In various embodiments and as shown in FIG. 4, the outer stopper 142 isformed to have a thickness thicker than that of the inner stopper 141(S1>S3).

As described above, in the present invention, the number of the voids131 and 132 formed in the cushion rubber 130, the shape of each void,and the number and shape of the stoppers 141 and 142 may vary.Accordingly, the rigidity characteristic zone of the center bearing bushunit can be subdivided and expanded, thereby effectively insulatingvibrations.

For example, in the present invention, the rigidity characteristic ofthe center bearing bush unit can be set to be subdivided/multi-leveledaccording to displacement conditions of vibrations input to thepropeller shaft, such as when a contact between the cushion rubber 130and the stopper 141 and 142 does not occur, when a contact of the innerstopper 141 with the wall surface of the inner void 131 occurs, and whena contact of the outer stopper 142 with the wall surface of the outervoid 132 occurs.

The center bearing bush unit configured as described above may beconfigured into a structure having openings as shown in FIG. 5A, or maybe configured into a basic structure having no opening.

In a case where it is required to differently implement insulationcharacteristics in the vertical or lateral direction depending on achange in operational environment of the center bearing bush unitmounted in the vehicle, openings 133, 143 and 144 may be formed in thecushion rubber 130 and the stoppers 141 and 142 as shown in FIGS. 5A,6A, 6B, 7A, and 7B.

For example, the cushion rubber 130 may have a plurality of openings 133arranged along the circumferential direction thereof.

As shown in FIGS. 6A and 6B, the opening 133 may be formed into astructure punched in the wall surface of the cushion rubber surroundingthe inner void 131.

In this case, the opening 133 may have a structure opened at an end ofthe inner circumferential surface (portion attached to the outercircumferential surface of the inner pipe 110) of the cushion rubber130.

For example, at least one of the inner and outer stoppers 141 and 142may have a plurality of openings 143 and 144 arranged along thecircumferential surface thereof.

As shown in FIG. 7B, the opening 143 of the inner stopper 141 may bepunched into the sectional structure of a‘

’ shape by being extended from the inner circumferential surface of theinner stopper 141, attached to the outer circumferential surface of theinner pipe 110, to one end portion of the inner stopper 141, insertedinto the inner void 131 of the cushion rubber 130, and the opening 144of the outer stopper 142 may be punched into the sectional structure ofa‘

’ shape by being extending from the inner circumferential surface of theouter stopper 142, attached to the outer circumferential surface of theinner pipe 110, to one end portion of the outer stopper 142, insertedinto the outer void 132 of the cushion rubber 130.

In this case, one side of the opening 143 of the inner stopper 141,inserted into the inner void 131 of the cushion rubber 130, may beopened, and one side of the opening 144 of the outer stopper 142,inserted into the outer void 132 of the cushion rubber 130, may beopened.

The plurality of openings 133, 143 and 144 arranged in thecircumferential directions in the cushion rubber 130 and the stoppers141 and 142 may be formed into the same structure, or may be formed intodifferent structures when necessary.

In addition, the plurality of openings 133, 143 and 144 arranged in thecircumferential directions in the cushion rubber 130 and the stoppers141 and 142 may be arranged at the same interval, or may be arranged atdifferent intervals.

FIG. 8 is a schematic view showing shapes obtained by variably applyingthe thickness of the cushion rubber in a circumferential directionaccording to the present invention.

In a case where a change in insulation characteristic is required due toa change in operational environment of the center bearing bush unitmounted in the vehicle, the required insulation characteristic may beimplemented by tuning the thicknesses of the cushion rubber 130 and thestoppers 141 and 142.

For example, in a case where the insulating characteristic of the centerbearing bush unit is differently implemented along the circumferentialdirection due to a change in operational environment, the thicknessesTup, Tdown, Tleft and Tright of the cushion rubber may be formed toincrease/decrease by being varied along the circumferential direction asshown in FIG. 8.

The stopper of the thicknesses of the stopper may also be formed toincrease/decrease by being varied along the circumferential direction,so that the insulation characteristic of the center bearing bush unitcan be variably implemented along the circumferential direction.

In other words, the thicknesses of any one or both of the cushion rubber130 and the stoppers 141 and 142 may be variably formed along thecircumferential direction, so that the insulation characteristic of thecenter bearing bush unit can be variably implemented along thecircumferential direction.

That is, the thicknesses of any one or both of the cushion rubber 130and the stopper 141 and 142 are varied, so that the insulationcharacteristic of the center bearing bush unit can be varied.

Thus, each of the cushion rubber 130 and the stopper 141 and 142 mayhave a constant thickness in the circumferential direction, or may havea variable thickness in the circumferential direction.

FIG. 9 is an exemplary view showing voids of the cushion rubber andapplications of the stopper according to the present invention.

As described above, the voids 131 and 132 are formed in the cushionrubber 130 in order to reduce the amount of small-displacement movementcaused during driving of the vehicle and to decrease vibrationtransmissibility. Therefore, as shown in FIG. 9 (a) to (f), the void maybe formed to have various sectional structures including a quadrangularshape, a trapezoid shape, a quadrangular shape having a round end, aquadrangular shape having a sloped end, etc. The void may also have asectional structure having a triangular shape.

As shown in (g) to (i) of FIG. 9, the shape of the stopper 141 and 142is variously modified and applied to a sectional structure having asimple quadrangular end, a sectional structure having a quadrangularshape of which end is gradually narrowed, a sectional structure having aquadrangular shape of which end is gradually widened, etc. in order toreduce the amount of small-displacement movement caused during drivingof the vehicle and to decrease the vibration transmissibility.Accordingly, the insulation characteristic of the center bearing bushunit can be implemented to cope with a change in operationalenvironment.

As described above, in the present invention, the cushion rubber and thestopper for vibration insulation of the propeller shaft areindependently configured, and the shapes of the cushion rubber and thestopper are simplified, so that the void of the cushion rubber and theshape of the stopper can be variously applied according to a desiredvibration insulation characteristic or rigidity characteristic. Inaddition, the stopper is configured in plural numbers, so that thedurability of the center bearing bush unit can be maintained identicalto or more than that of the existing center bearing bush units.

Further, in the present invention, the fillet radius of the bent portionof each of the cushion rubber and the stopper can be adjusted, therebyimproving the durability of the center bearing bush unit. Accordingly,the amount of displacement caused by the weight of the propeller shaftis absorbed, so that it is possible to improve vibration insulationafter the propeller shaft is mounted in the vehicle.

That is, in the present invention, a plurality of voids and a pluralityof stoppers are used as variables and conditions for changing thevibration insulation characteristic, and a wide rigidity characteristiczone is implemented, so that it is possible to cope with vibrations ofvarious displacements from a small-displacement vibration occurringduring driving to a large-displacement vibration occurring inoscillation, thereby improving the vibration insulation performance ofthe center bearing bush unit.

FIG. 10 is a graph showing a rigidity of the center bearing bush unit inthe diameter direction according to various embodiments of the presentinvention.

As shown in FIG. 10, in a case where the stopper is configured with asingle stopper, the center bearing bush unit has a two-stepcharacteristic zone through a stopper non-contact and a stopper contact.In a case where the stopper is configured with inner and outer stoppers,the center bearing bush unit has at least a three-step characteristiczone through a stopper non-contact, an inner stopper contact, an outerstopper contact, etc. Accordingly, when a vibration occurs in thepropeller shaft, the rigidity characteristic zone is subdivided and morewidely formed, thereby effectively insulating vibrations.

For example, when a middle-displacement vibration occurs, the rigidityis low in the existing center bearing bush unit, and therefore, it isimpossible to perform an effective displacement control. However, in thepresent invention, the rigidity characteristic zone is more widelysubdivided, and thus it is possible to cope with the middle-displacementvibration.

In addition to the tuning and changing of the shapes of the cushionrubber and the stopper so as to vary the vibration insulationcharacteristic as described above, it is possible to vary acharacteristic of decreasing the amount of small-displacement vibrationby changing the material of the cushion rubber, and it is possible tovary a characteristic of decreasing the amount of large-displacementvibration by changing the material of the stopper.

In this case, the shapes and materials of the cushion rubber and thestopper can be independently designed/tuned, and thus the freedom degreein designing and tuning the center bearing bush unit is improved.Accordingly, it is possible to rapidly cope with a variable situationsuch as a change in bending angle of the propeller shaft due to a changein mounting position or layout when the center bearing bush unit ismounted in the vehicle. Further, it is possible to shorten a developmentperiod of the center bearing bush unit and to reduce developing cost ofthe center bearing bush unit.

Meanwhile, various embodiments capable of performing functions equal tothose of the aforementioned embodiment shown in FIG. 4 will bedescribed.

FIG. 11 is a sectional configuration view showing a center bearing bushunit for a propeller shaft according to various embodiments of thepresent invention.

As shown in FIG. 11, the center bearing bush unit according to variousembodiments of the present invention may be configured into a structurein which inner and outer stoppers 141 and 142 are attached to the innercircumferential surface of an outer pipe 120.

Specifically, the center bearing bush unit may include an inner pipe110, an outer pipe 120 disposed on a common axis as the inner pipe 110at the outside of the inner pipe 110, a cushion rubber 130 attachedbetween the inner and outer pipes 110 and 120 and having inner and outervoids 131 and 132 disposed on a common axis, and inner and outerstoppers 141 and 142 attached to the inner circumferential surface ofthe outer pipe 120 while being spaced apart from the cushion rubber 130at a predetermined interval.

Like the aforementioned embodiments, the inner and outer voids 131 and132 may be formed to have the same width (D1 and D2), or may be formedto have different widths (D1 and D2).

In this case, the inner void 131 is formed adjacent to the innercircumferential surface of the cushion rubber 130, and the outer void132 is formed adjacent to the outer circumferential surface of thecushion rubber 130.

The inner and outer stoppers 141 and 142 are formed to have differentinside diameters. One end portion of the inner stopper 141 is insertedinto the inner void 131 of the cushion rubber 130 in a state in whichthe outer circumferential surface of the inner stopper 141 is attachedto the inner circumferential surface of the outer pipe 120. One endportion of the outer stopper 142 is inserted into the outer void 132 ofthe cushion rubber 130 in a state in which the outer circumferentialsurface of the outer stopper 142 is attached to the innercircumferential surface of the outer pipe 120.

In this case, the inner and outer stoppers 141 and 142 may be formed tohave different thicknesses (S1 and S3), or may be formed to have thesame thickness (S1 and S3).

FIG. 12 is a sectional configuration view showing a center bearing bushunit for a propeller shaft according to various embodiments of thepresent invention. FIG. 13 is a sectional configuration view showing acenter bearing bush unit for a propeller shaft according to otherembodiments of the present invention.

As shown in FIG. 12, the center bearing bush unit may be configured intoa structure in which an inner stopper 141 is attached to the outercircumferential surface of an inner pipe 110, and an outer stopper 142is attached to the inner circumferential surface of an outer pipe 120.

Specifically, the center bearing bush unit may include an inner pipe110, an outer pipe 120 disposed on a common axis as the inner pipe 110at the outside of the inner pipe 110, a cushion rubber 130 attachedbetween the inner and outer pipes 110 and 120 and having inner and outervoids 131 and 132 disposed on a common axis, and inner and outerstoppers 141 and 142 disposed while being spaced apart from the cushionrubber 130 at a predetermined interval. Here, the outer stopper 142 isattached to the inner circumferential surface of the outer pipe 120, andthe inner stopper 141 is attached to the outer circumferential surfaceof the inner pipe 110.

In this case, one end portion of the inner stopper 141 is inserted intothe inner void 131 of the cushion rubber 130 in a state in which theinner circumferential surface of the inner stopper 141 is attached tothe outer circumferential surface of the inner pipe 110, and one endportion of the outer stopper 142 is inserted into the outer void 132 ofthe cushion rubber 130 in a state in which the outer circumferentialsurface of the outer stopper 142 is attached to the innercircumferential surface of the outer pipe 120.

As shown in FIG. 13, the center bearing bush unit may be configured intoa structure in which an inner stopper 141 is attached to the innercircumferential surface of an outer pipe 120, and an outer stopper 142is attached to the outer circumferential surface of the inner pipe 110.

Specifically, the center bearing bush unit may include an inner pipe110, an outer pipe 120 disposed on a common axis as the inner pipe 110at the outside of the inner pipe 110, a cushion rubber 130 attachedbetween the inner and outer pipes 110 and 120 and having inner and outervoids 131 and 132 disposed on a common axis, and inner and outerstoppers 141 and 142 disposed while being spaced apart from the cushionrubber 130 at a predetermined interval. Here, the outer stopper 142 isattached to the outer circumferential surface of the inner pipe 110, andthe inner stopper 141 is attached to the inner circumferential surfaceof the outer pipe 120.

In this case, one end portion of the inner stopper 141 is inserted intothe inner void 131 of the cushion rubber 130 in a state in which theouter circumferential surface of the inner stopper 141 is attached tothe inner circumferential surface of the outer pipe 120, and one endportion of the outer stopper 142 is inserted into the outer void 132 ofthe cushion rubber 130 in a state in which the inner circumferentialsurface of the outer stopper 142 is attached to the outercircumferential surface of the inner pipe 110.

Like the aforementioned embodiments, in the center bearing bush unitsshown in FIGS. 12 and 13, the inner and outer voids 131 and 132 may beformed to have the same width (D1 and D2), or may be formed to havedifferent widths (D1 and D2).

In this case, the inner void 131 is formed adjacent to the innercircumferential surface of the cushion rubber 130, and the outer void132 is formed adjacent to the outer circumferential surface of thecushion rubber 130.

In addition, the inner and outer stoppers 141 and 142 may be formed tohave different thicknesses (S1 and S3) (S2 and S4), or may be formed tohave the same thickness (S1 and S3) (S2 and S4).

For convenience in explanation and accurate definition in the appendedclaims, the terms upper or lower, and etc. are used to describe featuresof the exemplary embodiments with reference to the positions of suchfeatures as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. A center bearing bush unit for a propeller shaft,comprising: an inner pipe; an outer pipe disposed on a common axis withthe inner pipe at an outside of the inner pipe; a cushion rubberattached between the inner and outer pipes, and having a plurality ofvoids disposed around the common axis and the plurality of voidsincludes an inner void and an outer void; an outer stopper attached toan outer circumferential surface of the inner pipe while being spacedapart from the cushion rubber at a predetermined interval; and an innerstopper attached to an inner circumferential surface of the outer pipewhile being spaced apart from the cushion rubber at a predeterminedinterval, wherein a first one end portion of the inner stopper isinserted into the inner void of the cushion rubber in a state in whichan outer circumferential surface of the inner stopper is attached to theinner circumferential surface of the outer pipe, and a first end portionof the outer stopper is inserted into the outer void of the cushionrubber in a state in which an inner circumferential surface of the outerstopper is attached to the outer circumferential surface of the innerpipe, wherein each distal end of the outer stopper and the inner stopperis curved in a parallel direction of the common axis toward the cushionrubber to form the first end portions of the inner and outer stoppersrespectively so that each first end portion of the inner and outerstoppers is inserted into the corresponding inner and outer voids,respectively, and wherein the inner stopper and the outer stopper areconfigured to selectively contact the cushion rubber.
 2. The centerbearing bush unit of claim 1, wherein the plurality of voids provided inthe cushion rubber are formed to have an identical width.
 3. The centerbearing bush unit of claim 1, wherein the inner void is disposedadjacent to an inner circumferential surface of the cushion rubber, andthe outer void is disposed adjacent to an outer circumferential surfaceof the cushion rubber.
 4. The center bearing bush unit of claim 1,wherein the inner and outer stoppers are formed to have an identicalthickness.